Added sugars in foods and beverages, particularly those based on fructose, are seen as a principal factor in diabetes and pre-diabetes, say researchers who urge a change in current dietary guidelines.
Those guidelines, which presently allow added sugars to constitute 25 percent of daily calories, should be drastically reduced, especially in terms of fructose, they say.
Clinical experts made those recommendations in an article in the Mayo Clinic Proceedings.
"At current levels, added-sugar consumption, and added-fructose consumption in particular, are fueling a worsening epidemic of type 2 diabetes," says lead author James J. DiNicolantonio, a cardiovascular research scientist at Saint Luke's Mid America Heart Institute in Kansas City, MO.
"Approximately 40 percent of U.S. adults already have some degree of insulin resistance with projections that nearly the same percentage will eventually develop frank diabetes," he says.
Current dietary guidelines should be changed to encourage people to consume more whole fruits and vegetables rather than processed food with added sugar, the experts say.
"Most existing guidelines fall short of this mark at the potential cost of worsening rates of diabetes and related cardiovascular and other consequences," they wrote.
The researchers say guidelines should follow World Health Organization recommendations that such added sugars should account for a maximum of 10 percent of a person's entire daily caloric intake.
In the United States, around 29 million adults -- 1 in 11 people -- suffer from type 2 diabetes, while another 86 million have "borderline" diabetes, with blood sugar levels higher than is considered healthy.
Worldwide, the number of people with diabetes has more than doubled, from 153 million in 1980 to 347 million in 2008.
Analysis of clinical trials and observational studies suggests excessive consumption of fructose is responsible for insulin resistance and can have metabolic consequences such as increased cholesterol and elevated blood pressure, the researchers say.
Although fructose occurs naturally in foods including fruits and vegetables, it is at much lower concentration than what is often found in processed foods, they point out.
Around 75 percent of all packaged foods and beverages sold in the United States contain added sugars, they report.
"There is no biological need for any added sugars in the diet, particularly those containing fructose," they conclude in their article. "At an individual level, limiting consumption of foods and beverages that contain added sugars, particularly added fructose, may be one of the most effective strategies for ensuring one's robust future health."
